The present invention relates generally to means of cooling the surface of skin during laser treatment (for example, for so-called laser resurfacing), the aim being to reduce the sensitivity to pain, reduce the need for anaesthetic or both. More particularly, the present invention relates to a laser treatment cooling head and, particularly, to a cooling head which can be used with a CO2 or other laser employed for laser treatment of a patient""s skin.
The advent of easily usable laser equipment has led to a great increase in this kind of treatment, but the problem of the control of pain, which can be severe as the process is essentially one of burning away skin, remains an obstacle to the wider use of the technique. In particular, according to clinical judgment and patient tolerance of pain, a general or local anaesthetic may be necessary. The use of a general anaesthetic enables the clinician to proceed rapidly with the treatment without constant checking of the comfort of the patient, but carries the severe drawbacks of the well known trauma of general anaesthetics, including the risk and the need for a recovery time before the patient resumes normal life, the need for an anaesthetist and the time for preparation and recovery. The latter two, in particular, make the cost of the treatment very high. In contrast, use of a local anaesthetic can allow a dermatologist to administer the anaesthetic, but again there are drawbacks. Pain control over certain areas of the body, particularly the face, requires multiple injection sites which is traumatic for the patient and the need for top-up doses during treatment is also unpleasant for the patient, also slowing down the treatment. The total dose of local anaesthetic is also limited which can therefore limit a particular treatment session, thus requiring further sessions and associated increased cost.
It has been proposed to use localised cooling to overcome the problems of anaesthesia and, in particular, it has been proposed to utilise a flow of coolant through a laser-transparent glass chamber which can be held against the skin while the laser treatment is carried out. However, this is only possible with visible light lasers, not with CO2, Erbium YAG (yttrium aluminium garnet), or Holmium lasers, as existing cooling devices use coolants and windows that are not lucent to the wavelengths of CO2, Erbium YAG, or Holmium radiation, i.e. current cooling devices using water would absorb the energy at these wavelengths so skin treatment would be impossible.
According to a first aspect of the present invention, there is provided a cooling head for a skin treatment laser, the cooling head comprising
a metal or other thermally conductive body having
a mount disposed at one end for attachment to a laser head to secure the metal body relative to the head in a fixed position;
a cooling surface at the other end for application to a patient""s skin and having an aperture therethrough;
a bore extending from the mount through the body to the aperture in the cooling surface to allow a laser beam to be passed therethrough to a treatment area of the patient""s skin;
an extraction port for enabling removal of debris from the treatment area and for connection to a vacuum source; and
an optically transparent window disposed in the body to allow the treatment area at the aperture in the cooling surface to be viewed by a surgeon using the laser; and
a cooling means provided in or on the body to enable heat removal from the body in use in order to cool the cooling surface.
The cooling means may be a coolant passage for example or an electronic cooling means such a Peltier device. For increased flexibility of use, both may be incorporated and used together or separately, say at different times during treatment.
Using a metal body enables a relatively large mass of cold material to be provided as, in effect, a store of refrigerated material, ensuring that cooling around the treatment area can be maintained with a high degree of certainty. The mount may be integral with or separate to the metal body itself.
The optically transparent window disposed in the body may, at its simplest, be provided by simple open section, slot, bore or other aperture in the side wall of body which may be angled towards the aperture in the cooling surface or otherwise provide a line of sight to the aperture. For example, the body may be substantially C or U-shaped in cross-section, ie part of the side wall being either removed or else being left out during manufacture to allow direct vision of the inside of the body and the treatment area, in which case, the aperture at the other end of the body may be co-extensive with the window. In an alternative construction the optically transparent window may be solid, eg glass, and may be a lens.
Preferably, when a coolant passage is employed, it comprises one or more coolant pathways either formed through the metal body or disposed on the exterior of the metal body in intimate contact with the body, to form a heat exchanger. For example, the coolant passage may comprise a helically wound copper tube soft-soldered in contact with a brass body. The coolant may be simply water, brine or another liquid refrigerant and is preferably designed to maintain the cooling surface, ie the contact point of the cooling head with the patient""s skin, at a temperature of between xe2x88x9220xc2x0 C. and +4xc2x0 C., which temperature may be arranged to be adjustable. However, in an alternative construction, the pathways for coolant may be provided directly within the metal body and the coolant may be a low temperature, laser lucent, gas such as nitrogen (which is lucent to CO2, Erbium YAG, or Holmium laser wavelengths), in which case the nitrogen may be provided to the central bore and may be removed through the extraction port together with debris, by a suitable vacuum pump or the like.
Particularly in constructions where the coolant flows within the head, feedback temperature control of the head may be provided so that the surgeon can set a temperature which is a compromise between the feeling of discomfort from the cold and the laser. The temperature range available should be xe2x88x9220xc2x0 C. to +4xc2x0 C. The feedback system may comprise one or more temperature sensors in the head so that the temperature or flow rate or both of the coolant can be adjusted to maintain the desired temperature. For convenience the temperatures of one or more sites in the head can be displayed electronically to the surgeon.
Providing an extraction port to allow extraction of debris and debris vapour reduces the risk of pollution of the treatment area with debris vapour.
According to a second aspect of the present invention, there is provided a cooling head for a skin treatment laser, the cooling head comprising
a body having
a mount disposed at one end for attachment to a laser head to secure the body relative to the head in a fixed position;
a surface at the other end for application to a patient""s skin and having an aperture therethrough;
a coolant passage through the body to enable a fluid coolant to be passed to a treatment area of the patient""s skin through the surface, in use in order to cool the patient""s skin;
an extraction passage through the body for enabling removal of coolant and debris from the treatment area;
a bore or passage extending from the mount through the body to the aperture in the cooling surface to allow a laser beam to be passed therethrough; and
an optically transparent window disposed in the body to allow the treatment area at the aperture in the surface to be viewed by a surgeon using the laser.
In a first embodiment, the coolant passage connects with the aperture in the surface to enable coolant to be provided to the patient""s skin at the point of application of the laser beam. This is preferably achieved by forming the surface of the body simply from the contiguous end faces of a sidewall or sidewalls, defining the sides of a chamber which forms the coolant passage, so that the aperture is provided as the open end of the chamber between the sidewall end faces.
In a second embodiment, the coolant passage passes through the body and the surface at a location adjacent the aperture to enable coolant to be provided to the patient""s skin adjacent the point of application of the laser beam.
In both cases, the body may be at least partly formed of metal adjacent the surface in order to enable the surface to be cooled by the flow of coolant through or around the body so as to provide an additional measure of cooling to the patient""s skin by the application of the cooled surface to the skin.
A CO2 laser would be incapable of use with the prior art systems mentioned above and therefore the present invention enables the direct application of, for example, CO2, Erbium YAG, or Holmium laser energy to the skin, whilst ensuring that both satisfactory cooling and required visibility for the surgeon are maintained.
The optically transparent window disposed in the body may be provided by a windowed aperture in an angled side wall of body facing towards the aperture in the cooling surface. The optically transparent window may be solid, eg glass and may be in the form of a lens to magnify the treatment area.
Preferably the mount comprises an annular counter-bore at the open end of the bore and has fastenings for securing a laser head in a defined position within the counter-bore.
The surface applied to the patient""s skin may be substantially flat or significantly curved, depending on the precise application, ie the particular area of the skin to be treated. For example, when treating significantly concave areas of the skin, such as adjacent the nose, a convex surface in necessary in order that as much of the surface as possible can engage the skin to provide an effective seal with the skin.
Preferably, the coolant passage according to the second aspect of the invention, comprises inlet and outlet ports and an internal chamber formed within the body and opening to the patient""s skin through the surface. The coolant may be a low temperature gas such as nitrogen which may be removed through the extraction port together with debris, by a suitable vacuum pump or the like.
A light may be provided within the chamber to illuminate the treatment area.